21997969920 has 240 divisors, whose sum is σ = 76701822912. Its totient is φ = 5826355200.

The previous prime is 21997969919. The next prime is 21997969921. The reversal of 21997969920 is 2996979912.

It is an interprime number because it is at equal distance from previous prime (21997969919) and next prime (21997969921).

It is a tau number, because it is divible by the number of its divisors (240).

It is not an unprimeable number, because it can be changed into a prime (21997969921) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3475879 + ... + 3482201.

Almost surely, 2^21997969920 is an apocalyptic number.

21997969920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21997969920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38350911456).

21997969920 is an abundant number, since it is smaller than the sum of its proper divisors (54703852992).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21997969920 is a wasteful number, since it uses less digits than its factorization.

21997969920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6503 (or 6484 counting only the distinct ones).

The product of its (nonzero) digits is 9920232, while the sum is 63.

The spelling of 21997969920 in words is "twenty-one billion, nine hundred ninety-seven million, nine hundred sixty-nine thousand, nine hundred twenty".